1. Probe Request and Response in TGai
October 2011
doc.: IEEE /1414r0
October 2011
Probe Request and Response in TGai
Date:
Authors:
Katsuo Yunoki, KDDI R&D Laboratories
Katsuo Yunoki, KDDI R&D Laboratories

2. October 2011
doc.: IEEE /1414r0
October 2011
Abstract
This document describes a technical proposal for TGai which addresses the following phase.
AP Discovery
Katsuo Yunoki, KDDI R&D Laboratories
Katsuo Yunoki, KDDI R&D Laboratories

3. Conformance w/ TGai PAR & 5C
October 2011
doc.: IEEE /1414r0
October 2011
Conformance w/ TGai PAR & 5C
Conformance Question
Response
Does the proposal degrade the security offered by Robust Security Network Association (RSNA) already defined in ? No
Does the proposal change the MAC SAP interface?
Does the proposal require or introduce a change to the architecture?
Does the proposal introduce a change in the channel access mechanism?
Does the proposal introduce a change in the PHY?
Which of the following link set-up phases is addressed by the proposal?
(1) AP Discovery (2) Network Discovery (3) Link (re-)establishment / exchange of security related messages (4) Higher layer aspects, e.g. IP address assignment 1
Katsuo Yunoki, KDDI R&D Laboratories
Katsuo Yunoki, KDDI R&D Laboratories

4. October 2011
doc.: IEEE /1414r0
October 2011
Background
Time occupied situation in the real case was presented in Doc. 寄与文書案(1)r.
The time occupied rate will become higher and higher because of Smartphone increasing.
Thus, we have to consider reducing needless packet exchanges which occur packet collisions and bigger latency in order to obtain the FILS advantages effectively.
Katsuo Yunoki, KDDI R&D Laboratories
Katsuo Yunoki, KDDI R&D Laboratories

5. Probe Request / Response
October 2011
doc.: IEEE /1414r0
October 2011
Probe Request / Response
In order to search the surrounding APs, a STA receives Beacon and transmit Probe Request in Broadcast.
APs transmit Probe Response for responding received Probe Requests in unicast.
STA
AP1
AP2
AP3
AP4
Probe Request (wildcard)
Probe Response
Katsuo Yunoki, KDDI R&D Laboratories
Katsuo Yunoki, KDDI R&D Laboratories

6. Example of Probe Request
October 2011
doc.: IEEE /1414r0
October 2011
Example of Probe Request
This STA transmits multiple “Probe Request” about every 15 seconds.
5 Probe Requests were observed around time stamp of 104 seconds. No
Time
source
destination
Info
48:XX:bc:bc:a3:XX
Broadcast
Probe Request, SN=2207, FN=0, Flags= C, SSID=Broadcast
Probe Request, SN=2208, FN=0, Flags= C, SSID=Broadcast
Probe Request, SN=2209, FN=0, Flags= C, SSID=Broadcast
Probe Request, SN=2210, FN=0, Flags= C, SSID=Broadcast
Probe Request, SN=2211, FN=0, Flags= C, SSID=Broadcast
Probe Request, SN=2212, FN=0, Flags= C, SSID=Broadcast
Probe Request, SN=2229, FN=0, Flags= C, SSID=Broadcast
Probe Request, SN=2231, FN=0, Flags= C, SSID=Broadcast
Probe Request, SN=2232, FN=0, Flags= C, SSID=Broadcast
Probe Request, SN=2233, FN=0, Flags= C, SSID=Broadcast 1
Probe Request, SN=2251, FN=0, Flags= C, SSID=Broadcast 2
Probe Request, SN=2252, FN=0, Flags= C, SSID=Broadcast 3
Probe Request, SN=2253, FN=0, Flags= C, SSID=Broadcast 4
Probe Request, SN=2254, FN=0, Flags= C, SSID=Broadcast 5
Probe Request, SN=2255, FN=0, Flags= C, SSID=Broadcast
Probe Request, SN=2273, FN=0, Flags= C, SSID=Broadcast
Probe Request, SN=2274, FN=0, Flags= C, SSID=Broadcast
Probe Request, SN=2275, FN=0, Flags= C, SSID=Broadcast
Probe Request, SN=2276, FN=0, Flags= C, SSID=Broadcast
Probe Request, SN=2277, FN=0, Flags= C, SSID=Broadcast
Probe Request, SN=2278, FN=0, Flags= C, SSID=Broadcast
* Source MAC address was modified.
Katsuo Yunoki, KDDI R&D Laboratories
Katsuo Yunoki, KDDI R&D Laboratories

7. Example of Probe Response
October 2011
doc.: IEEE /1414r0
Example of Probe Response
October 2011
3 SSID were responded for probe requests.
26 probe responses were observed for 5 probe requests in Slide 7. No
Time stamp
source
destination
Into 1
Matsushi_c5:XX:c0
48:XX:bc:bc:XX:2b
Probe Response, SN=1983, FN=0, Flags=..m.....C, BI=100, SSID=AAA 2
Matsushi_c5:XX:c1
Probe Response, SN=1984, FN=0, Flags=..m.....C, BI=100, SSID=BBB 3
Probe Response, SN=1984, FN=0, Flags=..m.R...C, BI=100, SSID=BBB 4 5
Matsushi_c5:XX:c6
Probe Response, SN=1985, FN=0, Flags= C, BI=100, SSID=CCC 6
Probe Response, SN=1985, FN=0, Flags=....R...C, BI=100, SSID=CCC 7
Probe Response, SN=1989, FN=0, Flags=..m.....C, BI=100, SSID=AAA 8
Probe Response, SN=1990, FN=0, Flags=..m.....C, BI=100, SSID=BBB 9
Probe Response, SN=1991, FN=0, Flags= C, BI=100, SSID=CCC 10
Probe Response, SN=1992, FN=0, Flags=..m.....C, BI=100, SSID=AAA 11
Probe Response, SN=1992, FN=0, Flags=..m.R...C, BI=100, SSID=AAA 12 13
Probe Response, SN=1993, FN=0, Flags=..m.....C, BI=100, SSID=BBB 14
Probe Response, SN=1994, FN=0, Flags= C, BI=100, SSID=CCC 15
Probe Response, SN=1995, FN=0, Flags=..m.....C, BI=100, SSID=AAA 16
Probe Response, SN=1995, FN=0, Flags=..m.R...C, BI=100, SSID=AAA 17 18 19
Probe Response, SN=1996, FN=0, Flags=..m.....C, BI=100, SSID=BBB 20
Probe Response, SN=1996, FN=0, Flags=..m.R...C, BI=100, SSID=BBB 21 22 23
Probe Response, SN=1998, FN=0, Flags=..m.....C, BI=100, SSID=AAA 24
Probe Response, SN=1998, FN=0, Flags=..m.R...C, BI=100, SSID=AAA 25 26
Katsuo Yunoki, KDDI R&D Laboratories
Katsuo Yunoki, KDDI R&D Laboratories

8. October 2011
doc.: IEEE /1414r0
October 2011
Considerations
“Probe Request / Response” cause packet flooding even if the STA doesn’t have any connecting capabilities to surrounding APs.
Transmitting “Probe Request” every 15 seconds doesn’t help the fast AP discovery.
Avoiding needless packets may bring clearer WLAN air circumstances.
Katsuo Yunoki, KDDI R&D Laboratories
Katsuo Yunoki, KDDI R&D Laboratories

9. Proposal I’d like to propose that:
October 2011
doc.: IEEE /1414r0
October 2011
Proposal
I’d like to propose that:
STA complied with TGai shall not use the wildcard SSID in SSID element of “Probe Request”.
AP complied with TGai shall not transmit “Probe Response” for “Probe Request” with the wildcard SSID.
I’d like to invite comments from experts.
Katsuo Yunoki, KDDI R&D Laboratories
Katsuo Yunoki, KDDI R&D Laboratories

10. References doc.: IEEE 11-11/1413r0 October 2011
Katsuo Yunoki, KDDI R&D Laboratories
Katsuo Yunoki, KDDI R&D Laboratories